1. Field of the Invention
The present invention relates to Internet Protocol (IP) network communication, and more particularly, to a method for using neighbor discovery messages to support mobility of Mobile Nodes (MNs) in a multi-hop wireless network and a network system therefor.
2. Description of the Related Art
Generally, nodes in an IP wireless network include a device such as a wireless sensor, which is required to physically connect with the actual application environments. For example, a wireless sensor for Personal Area Networks (PANs) is based on the IEEE 802.15.4 standard.
FIG. 1 illustrates the entire frame format for an IEEE 802.15.4 frame, the maximum size of which is 127 bytes and in which an Internet Protocol version 6 (IPv6) over Low power Wireless Personal Area Network (6LoWPAN) packet is included. 6LoWPAN refers to a simple low-cost communication network that provides a wireless connection environment to applications that require limited power and low throughput. The 6LoWPAN standard defines three types of headers: a dispatch header, a mesh header, and a fragmentation header.
The dispatch header is a header representing information about its succeeding headers. For example, Header Compression (HC) dispatch headers indicate compression information of an IP header or a User Datagram Protocol (UDP) header. That is, the IP header is maximally compressed by an HC1 dispatch header, and the UDP header is maximally compressed by an HC2 dispatch header. The mesh header is a header indicating information for mesh routing. The fragmentation header is a header indicating information for fragmentation and reassembly of the packet.
FIGS. 2A and 2B illustrate an operational difference between Mobile IPv6 technology and Proxy Mobile IPv6 technology.
FIG. 2A illustrates mobility management in Mobile IPv6. A mobile terminal (or an MN), in which inter-PAN mobility has occurred, performs binding update by directly communicating with a Home Agent (HA). In Mobile IPv6, the MN should have all mobility protocols necessary for communication since it plays an important role in mobility management.
FIG. 2B illustrates mobility management in Proxy Mobile IPv6. In Proxy Mobile IPv6, unlike in Mobile IPv6 of FIG. 2A, an MN does not take part in IP mobility protocol signaling. When the MN moves, an Access Router (AR) performs binding update by communicating with an HA. That is, in Proxy Mobile IPv6, mobility is managed from the viewpoint of the network.
In the conventional Mobile IPv6 scheme, only the MN with a complex option can receive an Internet service while on the move. However, in Proxy Mobile IPv6, even IPv6 nodes with no mobility protocol may receive the Internet service while on the move.
FIG. 3 illustrates a scenario in which an MN equipped with a mobility protocol directly manages mobility when a Mobile IPv6 protocol is applied.
In the Mobile IPv6 environment, an MN should perform binding update by directly communicating with an HA. Therefore, compared with when Proxy Mobile IPv6 is applied, the function the MN should implement is comparatively complex, and the MN must handle excessive signaling. Consequently, it is inappropriate to apply a mobility protocol such as Mobile IPv6 in order to support mobility of MNs for a network (e.g., IEEE 802.15.4-based 6LoWPAN) that has the limitations of low power, narrow bandwidth, small memory space, limited processing capability, etc.